The last book itself involved an elaborate plan.
There were to be three epistles about each cardinal virtue--one, for example, upon avarice; another on the contrary extreme of prodigality; and a third, upon the judicious mean of a moderate use of riches.

Pope told Spence that he had dropped the plan chiefly because his third book would have provoked every Church on the face of the earth, and he did not care for always being in boiling water.

The scheme, however, was far too wide and too systematic for Pope's powers.

His spasmodic energy enabled him only to fill up corners of the canvas, and from what he did, it is sufficiently evident that his classification would have been incoherent and his philosophy unequal to the task.

Part of his work was used for the fourth book of the Dunciad, and the remainder corresponds to what are now called the Ethic Epistles.